This invention is generally directed to resin compositions useful as toner and developer composition components. More specifically, the present invention relates to polyalkyl, especially branched polyalkyl, styrene butadiene resins such as acrylate styrene butadiene ternary copolymers useful for the formulation of toner compositions that can be selected for a number of imaging processes including those wherein silicone release oils are avoided. In one embodiment, there are provided in accordance with the present invention branched polyalkyl styrene/butadiene ternary copolymer resins that can be selected for the formulation of low melting, for example about 255.degree. F. to about 300.degree. F. in some embodiments, toner compositions containing, for example, pigment particles, and optional additive particles. In addition, the present invention is directed to processes for the preparation of the aforementioned resins by suspension free radical polymerization processes with short reaction times, and wherein products of high purity and high yields can be obtained. Processes for the preparation of the aforementioned polymers using free radical procedures can be accomplished by the emulsion polymerization techniques as illustrated in U.S. Pat. No. 4,469,770, and suspension polymerization processes as illustrated in U.S. Pat. No. 4,558,108, the disclosures of each of these patents being totally incorporated herein by reference. The low melting toner and developer compositions formulated with the branched polyalkyl resins illustrated herein are particularly useful in electrophotographic imaging and printing methods especially methods wherein soft roll fusers are selected. Further, the polyalkyl branched polymers of the present invention can be selected as emulsifiers to enable, for example, complete effective mixing of toner components such as blends of toner resins and release agents. In a specific embodiment of the present invention, there are provided low melting toners thereby enabling, for example, the advantage of decreased energy output from, for example, fuser rollers present in electrophotographic imaging and printing apparatuses enabling longer lifetime for such rollers. Moreover, by selecting lower fusing roll temperatures, there results decreased silicone oil volatility in situations wherein a silicone oil is employed thus less silicone oil is consumed and associated problems therewith are minimized and/or eliminated. The toners of the present invention in a number of embodiments possess a minimum fusing temperature of from about 255.degree. F. to about 275.degree. F., which temperature is effective and desirable for accomplishing the aforementioned advantages and other advantages.
A patentability search report cited the following prior art, all U.S. patents: U.S. Pat. No. 4,311,779 which discloses one component magnetic developers with certain binder components, reference for example columns 5 and 6 of this patent, and further note column 11, working Example 4, beginning at around line 50, and more specifically 55, wherein there was selected a thermoplastic resin vinyl toluene 2-ethylhexyl acrylate butadiene terpolymer; U.S. Pat. No. 3,853,778 directed to electrostatographic toners wherein the resin can be comprised of styrene and an alkyl methacrylate wherein the alkyl contains 14 carbon atoms or more, which polymers are sharp melting and exhibit rapid changes in melt viscosity, see column 4, and moreover, note column 4, line 50, wherein any suitable particulate resin having an amorphous backbone and side chain crystallinity imparted by C14 or longer alkyl group, a sharp melting point in the range of 40.degree. C. to 145.degree. C. and the other characteristics may be selected; and as background interest U.S. Pat. No. 3,980,576 directed to toner compositions with a resinous binder comprising a combination of thermoplastic resins based on a copolymer of styrene and an acrylate or methacrylate, which copolymer is combined with vinyl toluene butadiene, and wherein the developer particles have a melting index of 20 to 30 and a melting point of 75.degree. to 100.degree. C., reference the Abstract of the Disclosure, for example; U.S. Pat. No. 4,299,898 disclosing powder charged toners containing quaternary ammonium salts attached to acrylic polymers, reference for example the Abstract of the Disclosure; and U.S. Pat. No. 4,533,614 disclosing heat fixable dry toners wherein the binder resin comprises a nonlinear modified low melting polyester, reference the Abstract of the Disclosure, for example, and also note columns 7 and 8.
Toner and developer compositions, especially those containing charge enhancing additives, are well known, reference for example U.S. Pat. Nos. 3,893,935; 3,944,493; 4,007,293; 4,079,014 and 4,394,430. Thus, for example, there is described in U.S. Pat. No. 3,893,935 the selection of certain lower alkyl quaternary ammonium salts R.sub.4 N+X- as charge control agents for electrostatic toner compositions. Further, there are disclosed in U.S. Pat. No. 4,338,390 developer and toner compositions having incorporated therein as charge enhancing additives organic sulfate and sulfonate substances. A similar disclosure is present in U.S. Pat. No. 4,394,430. Moreover, there are disclosed in U.S. Pat. No. 4,298,672, the disclosure of which is totally incorporated herein by reference, positively charged toner compositions with resin particles and pigment particles; and as a charge enhancing additive, alkyl pyridinium compounds, inclusive of cetyl pyridinium chloride.
Additionally, toner and developer compositions useful in xerographic imaging processes wherein silicone oils are not needed are known, reference for example U.S. Pat. No. 4,556,624, the disclosure of which is totally incorporated herein by reference. In this patent, there are disclosed improved positively charged toner compositions comprised of a polyblend mixture of crosslinked copolymer compositions, a second polymer, pigment particles, and a particular wax component thereby enabling the toner compositions to be selected for imaging systems wherein release fluids can be eliminated. The types of resin described in this patent and other patents relating to toner compositions, including those compositions useful in imaging methods wherein release fluids are avoided include polyamides, epoxies, diolefins, polyurethanes, vinyl resins and polymeric esterification products of a dicarboxylic acid, and a diol comprising a diphenol. Typical monomers selected for the preparation of the appropriate aforementioned resins include styrene, p-chlorostyrene, unsaturated mono-olefins such as ethylene, propylene, butylene, isobutylene and the like; vinyl esters such as esters of monocarboxylic acids including methyl acrylate, ethyl acrylate, n-butylacrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methylalpha-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and other similar acrylates; acrylonitrile, methacrylonitrile, and acrylimide; vinyl ethers such as vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether, and the like; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopropenyl ketone, and N-vinyl indole, N-vinyl pyrrolidene, and the like; styrene butadiene copolymers, and mixtures thereof.
As preferred toner resins illustrated in the '624 patent, there can be selected styrene polymers, and the esterification products of a dicarboxylic acid, and a diol comprising a diphenol. The aforementioned polyesters are illustrated in U.S. Pat. No. 3,590,000, the disclosure of which is totally incorporated herein by reference. Other specific preferred toner resins include styrene/methacrylate copolymers; styrene/butadiene copolymers; polyester resins obtained from the reaction of bisphenol A and propylene oxide; followed by the reaction of the resulting product with fumaric acid; branched polyester resins resulting from the reaction of dimethylterephthalate, 1,3-butanediol, 1,2-propanediol, and pentaerythritol; styrene butadiene copolymers prepared by a suspension polymerization process, reference U.S. Pat. No. 4,558,108, the disclosure of which is totally incorporated herein by reference; styrene butadiene resins prepared by an emulsion polymerization process, reference U.S. Pat. No. 4,469,770, the disclosure of which is totally incorporated herein by reference; and Pliolites.
Furthermore, illustrated in U.S. Pat. No. 3,418,354 are processes for obtaining olefin-polyoxyalkylene copolymers by a graft reaction with a peroxide, whereby there are generated free radical sites on the backbone polymer. One process embodiment disclosed in the '354 patent involves the addition of an alpha olefin, such as styrene, and a peroxide to a polyoxyalkylene compound, such as a siloxane, wherein there results a graft copolymer; and more specifically, an olefin-polyoxyalkylene graft copolymer, see column 2, line 23. In Japanese Patent Publication 46-9355, there is disclosed a process for the preparation of graft block copolymers with a polysiloxane chain by the reaction of a functional polysiloxane with a polymer obtained from the anion polymerization of a styrene or a butadiene. Japanese Patent Publication 58-225103 discloses a method for the crosslinking of a thermoplastic resin by the reaction of a hydrogenated styrene-butadiene-styrene block copolymer with a silane in the presence of organic peroxides. Further, in U.S. Pat. No. 3,691,257 there are disclosed organic polymers modified by incorporating therein a siloxane polymer organic block copolymer; while Japanese Patent Publication 57-187345 describes a rubber modified styrene resin prepared by continuous bulk polymerizations in the presence of organic polysiloxanes and 1,2-vinyl polymers.
In U.S. Pat. No. 4,770,968, the disclosure of which is totally incorporated herein by reference, there are illustrated toner compositions with polysiloxane styrene butadiene copolymers of the formulas recited, for example, in the specification and Claim 1, which toners can be selected, for example, in xerographic imaging processes wherein no silicone release fluids are needed.
There is a need for low melting toners and for simple economical processes that enable the preparation of branched polyalkyl/styrene/butadiene resins in high yields exceeding 80 percent, for example, and wherein the resulting products are of an acceptable purity exceeding in most instances 98 percent. There is also a need for low melting, that is toners that have minimum fix temperatures of from about 255.degree. F. to about 300.degree. F. In addition, there is a need for toner resins that permit the formulation of toner compositions that possess desirable mechanical properties, excellent fusing characteristics, and acceptable release properties. Moreover, there is a need for developer compositions containing toner components, including the branched polyalkyl/styrene/butadiene copolymers illustrated herein, and carrier components. There is also a need for imaging and printing methods wherein there are selected toner and developer compositions containing the branched polyalkyl/styrene/butadiene copolymers disclosed herein. Moreover, there remains a need for low melting toner compositions that are compatible with fusing rolls incorporated into imaging apparatuses, especially Viton fuser rolls, and which compositions require less energy for fixing, for example, a temperature of about 25.degree. F. lower can be selected for melting the toner in some embodiments of the present invention compared to 25.degree. F. higher for conventional toners such as those containing styrene methacrylate, or styrene butadiene copolymer resins in place of the polyalkyl styrene butadiene copolymers of the present invention.
With further respect to the invention of the present application, particularly the developer compositions thereof, one Viton soft fuser roll selected for use in electrophotographic copying machines is comprised of a soft roll fabricated from lead oxide and DuPont Viton E-430 resin, a vinylidene fluoride hexafluoropropylene copolymer. This roll contains approximately 15 parts of lead oxide and 100 parts of Viton E-430, which mixture is blended and cured on the roll substrate at elevated temperatures. Apparently, the function of the lead oxide is to control the generation of unsaturation by dehydrofluorination which can cause crosslinking, and to provide release mechanisms for the toner composition.